Oscillation generator



Nov. 16 1926. 1,606,791

J. W. HORTON OSCILLATION GENERATOR Filed July 18, 1924 Patna n..... e-,

UNIT nf-STATES JOSEPH w. non'ron, or nLoomrmLn, NEW JERSEY, assmnon r wns'rnnn nmc'rnrc cournnr, mconronn'rnn, or NEW YORK, 11. Y., A conrorwrmu on NEW YORK.

OSGILLATION ennnna'ron.

Applicatibn filed m 18, 1924. Serial no. names.

This invention relates to oscillation generators and more articularly to spacedischarge tube oscil ators having means for preventing frequency variations of the generated oscillations.

In space discharge tube oscillators as heretofore designed, the output circuit has been coupled to the input circuit for the purpose of producing regeneration by means of reactive impedance devices such, for example, as condensers or transformers. These reactive coupling devices are known to have an influence u on the frequency of oscillations generated by theoscillator and to produce changes in its frequency. by

virtue of changes in'their reactance resulting from any cause such, for example, as changes in temperature, dielectric strength or ermeability of the parts of these devices. This results in the serious disadvantage that constant frequency oscillations can not be produced by an oscillator subjected to temperature or other variations nor canany simple adjustment be made to restore the system to stability at a readily predictable frequency since an adjustment of one quantity in the system is accompanied by a general readjustment of all the others.

In accordance with the resent invention the elements which are esigned and intended to control the frequnecy are soasso- 'ciated with other elements which might, be-

generate oscillations of constant frequency.

Another object is to control the fr uency of an oscillation generator indepen ently of reaction therefrom upon the control ele ment thereof.

A further object is to segregate the frequency control elements of an electrical oscillator from'other elements thereof;

A still further object is to control the power gam and phase shift of waves in an oscillation generator whereby, oscillations of only a desired frequency may be enerated.

A feature of the invention re ates to a space discharge tube oscillator having a frequency-control element, which is electrically independent of changes in the amplifying element. I

Another feature relates to a s ace discharge tube osci lator having its requency controlled by means of an element which is coupled to the amplifying element bymeans of non-reactive elements.

Another feature of the invention relates to an oscillation generator com rising a resonant circuit for controlling t e frequency of oscillations which is electrically segregated from the am lifying element. a

An additional eature concerns a space discharge 'tube oscillator having its frequency controlled by a 'iezo electric crystal arranged to be indepen ent of reaction from the amplifying element.

Another feature relates to a space discharge tube oscillator in which the frequency control element comprises anelectrically driven tuning fork the frequency of which is maintained independent of changes in the amplifier circuit.

A still further feature is a space discharge tube oscillator in which the frequency control element comprises a filter network resistance coupled to the amplifier.

This invention comprises a generator of oscillations having provided a frequency control element the parts of which are maintained substantially independent of influence from other. elements of the system'to prevent changes in frequency caused by reac tion upon this element of other elements of the system. The oscillation generator comprises an energy amplifying element and a frequenc control element. Means is also provided or supplying ener to a load device. The frequency contro element may consist of one or more component elements, at least one of which is so arranged as to have afrequency characteristic that is substantially unaffected by that of the associated amplifier element. The frequency control element is arranged to be supplied with only a small portion of the energy output from the energy amplifying element. By virtue of this fact the effect of fluctuations in the energy output of the oscillator upon the frequency control element is made negligible. In addition, the frequency control element or parts thereof are coupled to the energy amplifying element by means whose energy transfer efficiency remains unchanged with variations in the frequency of the energy. Hence, the frequency control element is rendered substantially unaffected by changes in reactance of other parts of the circuit tending to cause changes of frequency and also by changes in amplitude of the energy supplied thereto.

In the drawings:

Fig. 1 is a circuit diagram of a space dis charge tube oscillator having its frequency controlled by a series resonant circuit resistance coupled thereto.

Fig. 2 is a circuit diagram of an oscillation generator similar to that of Fig. 1 wherein the frequency control element is a filter network.

Fig. 3 is a circuit diagram of a space discharge tube oscillator having its frequency controlled by a resistance coupled piezo electric crystal.

Fig. 4 is a circuit diagram of an oscillation generator controlled as to frequency by means of a tuning fork.

Referring to Fig. 1, an oscillation generating system is illustrated which includes an energy amplifying element 10 and a frequency control element 11. The amplifying element comprises space dischargetubes 12 and 13 arranged in tandem and coupled by means of acondenser 14 and resistance 29. The input circuit of tube 12 and the output circuit of tube 13 are coupled by means of a feed back circuit 9. The circuit 9 includes the frequency control element 11 connected between coupling resistances 16 and 19.

The input circuit of tube 12 includes in series a grid polarizing battery 15 and resistance 16 and is connected to the grid and cathode of the tube. The output circuit of tube 13 includes condenser 17, high resistance 18, and low resistance 19 in series and isconnected to the anode and cathode of the tube. Leads 20 and 21 are associated with this output circuit for supplying any desired energy consuming load device. Lead 20 includes a resistance 65. The frequency control element 11 includes an adjustable inductance 22 and an adjustable capacity 23 connected between terminals of resistances 16 and 19. The opposite terminals of these resistances are connected together. Space current is supplied to tubes 12 and 13 by sources 24 and 25, illustrated as batteries, in series with choke coils 26 and 27 respectively.

The input circuit of tube 13 is coupled to the output circuit of tube 12. Suitable average polarizing potentials are supplied. to the grids of tubes 12 and 13 by batteries 15 and 28 the latter being in series with resistance 29.

it is designed with respect to the value of resistance 18 and the impedance of the load circuit connected to leads 20 and 21 due allowance being made for possible variations of these impedances in use.

Resistance 65 in lead 20 is large as compared to any load impedance connected to leads 20 and 21 and by this means changes in the output power are rendered negligible in their effect in producing variation of the damping of the inductance 22. Hence their effect in changing the resonant frequency of the tuned circuit is negligible. By the use of these coupling resistances 16 and 18 and 19 the system can be adjusted so that the several elements operate at that portion of their characteristics which insures maximum stability. By using resistance coupling instead of reactive coupling the parts of the amplifier element may be adjusted without substantial reaction upon the frequency controlling element. Also by adjustment of the frequency controlling element as by means of condenser 23 or inductance 22, the oscillator may be caused to oscillate at an easily predictable frequency.

In order to reduce the phase shift of energy through the amplifier element 10 the value of resistance 29 is made large as compared to the reactance of condenser 14.

In the operation of the system shown in Fig. 1 energy is supplied from the output circuit of tube 13 through the coupling resistance 19 to resonant element 11 and from this element energy of the frequency determined thereby is transmitted, through coupling resistance 16 to the input circuit of tube 12. This energy is amplified by tube 12 and transmitted through coupling condenser 14 to the input circuit of tube 13. Tube 13 produces further amplification of the energy and it is again supplied from the output circuit through the resonant element 11 and the coupling resistances to the input circuit of tube 12.

The resonant circuit 2223 is designed so that the phase of current therein changes with frequency at a high rate, hence, only a small change of frequency in the circuit is required to compensate for phase changes in other elements of the system.

Condenser 17 is provided to prevent the flow of direct current from battery 25 through the load circuit connected to leads 20 and 21.

In Fig. 2 is illustrated an oscillation generator which comprises an energy amplifying element 10 which is identical with the element 10 shown in Fig. 1. It also comprises a frequency control element 30 here 45 is therefore large as compared to the reillustrated .a' filter network. The element 30 is connected-between coupling resistances quency variation is an important consideration. 0

The operation of this system is substantially identical with that-of Fig. 1' and the'refore need not-be repeated.

In Fig. 3 an oscillation generating system is illustrated in which one part of the principal frequency control element 33 is a piezo electric device. This device may consist of-a crystal 39 cut from quartz in the shape of a parallelepiped and having metallic plates 40 adjacent to two opposite sides. The lates 40 are connected to terminals of reslstances 16 and 19 included in the feedback circuit 9 connected respectively to input and output circuits oftubes 12 and 13. A secondary frequency control element included in the system is a series resonant circuit 34-35 arrangedto couple the tubes 12 and 13 of the amplifier element. In series with the resonant circuit 34-35 is a series arran ement of a condenser 36 and a resistance 3 An additional coupling resistance 38 is connected to the junction between resistance 37 and inductance 34 and to the cathodes of tubes 12. and 13. The resistances 37 and 38 are provided to render the impedance of the tube output circuit substantially. non-reactive to prevent substantial phase changes in the current flowing therein. The value of these resistances actance of condenser 36.

The piezo electriccrystal 39 has a plurality of frequencies at which'it will produce a response, or in other Words, vibrate. It is a characteristic of such a crystal that on accountof its low damping at the frequencies to which it responds it causes 0s cillations to -be maintained at substantially constant frequency. However, in order to determine the particular one of its responsive freqllliencies at which the crystal shall vibrate't e series resonant circuit 3435 is provided as a supplementary frequency determining element. The circuit 34-35 is tuned to approximately the responsive frequency of the crystal at which 1t is desired to generate oscillations. The action of this resonant circuit isthen such that preference is given to that particular'resonant fref quency of the crystal 39. In other words, at i the desired frequency the impedance of the resonant circuit 34-35 is low, 'whereas at the other resonant frequencies of the crystal 39 the impedance of the resonant circuit 34-35'is very high, hence it serves to permit the generations of oscillations at the .de- I sired frequency and'to prevent oscillationsat other responsive frequencies of the crystal. By adjusting variable condenser 35,'the resonant circuit 3435 may be tuned so as to cause the generation of oscillations at any one of the desired frequencies at which the crystal 39 is responsive. The piezo electric device then operates to maintain the oscillations at this selected frequency within very narrow limits. The coupling resistances 16. and 19 serve to supply the necessary energy from the output circuit to the input circuit, to cause oscillation. Changes in the load connected to leads 20 and 21 are prevented from producing changes in the frequency of the oscillator, by their action upon the frequency controlling element, by' means of resistance 65, since a negligible percentage of the fluctuation is applied to the resonant piezo electric device.

An oscillation generating system is illustrated in Fig. 4 which includes as a frequency control element a tuning fork 41. The tuning fork 41 is'arranged to be maintained in vibration by drivmg magnet 42, the winding of which is connected in series with a polarizing battery 66 to the terminals of resistance 19 in the output circuit of amplifier tube 43. If desired battery 66 may be omitted and the magnet 42 may be polar-' ized by means of current from battery 25 by closing switch 67. As another alternative it may have a permanent magnetic core. The resistance 19 in this system may be relatively lar e. A pick-up magnet 60 is arranged a jacent to the prongs of tuning fork 41 and has its winding connected to the resistance 16 included in the input circuit of the space discharge tube 44. The core of magnet 60 is normally magnetized. The magnetization may be produced by providing a. permanent magnetic core or by means of a battery 45 connected in series with the winding of'magnet 60as shown.

The amplifier element in this system includes space discharge tubes 43 and. 44 in tandem with space discharge tube 46. Tubes 43 and-44 are coupled to the output and input circuits respectively of tube 46. Condensers 47 and 48 together with inductances 50 and 52 res 'ectively form resonant coupling circuits etween tubes 43 and 46 and, 44 and 46 respectively. To reduce the phase shift of energy through the amplifier element resistances 49, 55, 51 and '56 are provided as already explained. A condenser 57 is connected in series with a resistance 49 and aninductance 50 between the anode of the fork 41.

tube 46 and the, grid of tube. 43. A condenser 58 is connected in series with resistance 51 and inductance 52 to the anode of the tube 44 and the grid of tube 46. Condensers 57 and 58 are provided to prevent current from batteries 59 and 61 from flowing in the input circuits of tubes 43 and 46. Batteries 53 and 54 are provided for supplying suitable average polarizing potentials to the grids of tubes 43 and 46. Shunt resistances '55 and 56 are connected to the junctions between resistance 51 and inductance 52 and resistance 49 and inductance 50 respectively, and to the cathodes of tubes 43, 44 and 46.

The circuit of Fig. 4 has its frequency controlled by the tuning fork 41 in the same manner as the circuits of Figs. 1. 2 and 3 had their frequencies controlled by means of resonant elements 11, 30 and 33. Ener o supplied from the output circuit of tu e 43 is transmitted through resistance 19 to the winding of magnet 42. The magnet 42 acting upon the magnetic prongs of fork 41 causes the fork to vibrate at its natural frequency. The vibration of the prongs of fork 41 adjacent to the core of magnet 60 induces an alternating current in the winding of the magnet the frequency of which corresponds to the frequency of vibration of The energy of this current is transmitted through coupling resistance 16 to the input circuit of tube 44. Thisenergy is amplified by means of amplifier tubes 43, 44 and 46 and again supplied from the output circuit of tube 43 to the driving magnet 42. It is thus seen that sustained oscillations of constant amplitude and of constant frequency as determined by the natural frequency of the fork 4l may be generated by this system. The coupling resistances 16 .and 19 perform the same function in this arrangement as in the circuit of Figs. 1, 2 and 3. In this instance the resistance 19 may be considerably larger than in the other circuits in order to allow sufiicient current to drive the fork to pass to magnet 42. The changes in the current supplied to magnet 42 caused by variations of the load on the oscillator or otherwise are increased by increase of resistance 19 but because of the great inertia of the tuning fork these changes are not increased sufficiently to affect its frequency of vibration. The tuning fork 41 is designed to have a high rate of phase change with frequency the same as the control elements of the other figures in order that a change. of phase in the amplifier element may be compensated by a small change of frequency of the fork.

Although this invention has been illustrated as embodied in certain specific arrangements it is to be understood that its limitations are defined only by the scope of the appended claims.

What is claimed is:

1. An oscillation generator which coinprises an amplifying element, a frequency control element, and non-reactive means for coupling said control element to said amplifying element.

2. A s stem in accordance with claim 1 in which tlie frequency control element produces a large phase change per unit frequency change.

3. An oscillation generator which comprises an amplifying element, a frequency control element, and means for coupling said elements including non-reactive devices.

4. An oscillation generator which comprises an amplifying element, a resonant frequency control element, and means for coupling said elements to cause the generation of oscillations which comprises substantially wholly resistance.

5. An oscillation generator Which comprises a space discharge tube amplifying element, a frequency control element, and means comprisingnon-lnductive resistance for coupling said elements to cause the generation of oscil ations.

6. An oscillation generator which com prises a space discharge tube amplifying element, a resonant frequency control element, and non-reactive means for coupling said elements to cause the generation of constant frequency oscillations.

7. An oscillation generator which comprises a space discharge tube amplifying element, a frequency determining element, having a natural frequency of response, means for supplying oscillations to a load, and means for coupling said elements in energy transfer relation whereby said response frequency is held substantially fixed during variations of energy in said generator.

8. In an oscillation generator, an energy amplifying element and a frequency controlling element, said frequency controlling-element comprising a series resonant circuit, and means coupling said elements comprising non-reactive impedances.

9. In an oscillation generator, an energy amplifying element comprising a plurality of three-electrode space discharge tubes, a frequency controlling element, and means for coupling said frequency controlling element to an input and an output circuit of said tubes, said coupling means comprising non-reactive impede nces.

10. An oscillation generator which comprises an amplifying element, a frequency control element, and resistancecouplings associating the input and output circuits of said amplifier with said frequency control 125 element, whereby said fre uency control element is only negli ibly a acted by changes in condition of sai amplifying element.

11. In combination, an incoming circuit and an outgoing circuit, and means for coupling said circu'ts comprising a path including a resistance, a capacity and an inductance in series, and shunt resistances connected to electrically separate points in said path.

12. In combination, a wave generating device and a load circuit, means for preventing reaction of said load circuit upon said device comprisin a path including resistance, capacity an inductance elements in series and resistance elements in shunt.

13. In combination, two electrical circuits, one of said circuits being arranged for connection to a load device, means for coupling said circuits comprising a series tuned circuit connected between shunt resistances and another resistance connected series with Y said tuned circuit, said series resistance being large as compared to one of said shunt resistances.

14. In combination, two electrical c1rcu1ts, one of said c1rcu1ts being arranged for connection to a load device, means for coupling I said circuits comprising a resonant circuit connected between shunt resistances, and a my name this 16th day of July A. D., 1924.

JOSEPH W. HORTON. 

